I Prefer Shirtless Gyms
I actually had a membership at a small, local gym that allowed guys to workout shirtless and that was one of the main reasons I chose that gym.
I also worked out at a college gym that didn't "officially" allow shirtlessness, but unofficially it was cool as long as there weren't many people there. Five guys or less was usually cool, and I often worked out shirtless there.
Most bouldering gyms allow guys to climb shirtless and at one gym I was asked to wear a shirt only when using weightlifting equipment. I worked out on the punching bag in the same room shirtless and a lot of the guys went shirtless on the bouldering wall (which had its own room).